Dental casting machine



July 26, 1932. w. G. E. HARVEY DENTAL CASTING MACHINE Filed Aug. 13. 1930 Patented July 26, 1932 Unire sr WALTER G. E. HARVEYpOF LOS ANGELES, CALIFORNIA DENTAL CASTING- v- MACHINE application inea August" 13, 1930. serial No. 475,014.1 j

My invention relates to amachine for casting metal and more particularly toa machine that is especially designedfor use by dentists and in dental laboratoriesv for casting inlays, plates, bridges, saddles andthe like and the structure herein disclosed is an improvement on the casting machine disclosed in U. S. Letters Patent No. 1,320,228, issued to me August 28, 1919, also a somewhat similar dental casting machinethat. is set forth in my co-pending applicationfor U. S. Letters Patent tiled January 15,1930, Serial No. 420,878. 5 The principal objects of my presentinven` tionare, to generally improve upon and sim'- lplify the construction of the dental casting machine disclosed in my aforesaidpatent and patent application as well as otherj similar types of casting machines, further, to` provide a dental casting machine that is very compact and which may be conveniently employed for the rapid and economical production of small castings and particularlycast ings of precious metal that are utilized .A in

dental practice and further,"tovprovide amachine of the character referred to having al blow-pipe arranged so aste direct ajet of burningV gasy directly against the metal that is to be melted and forced intothe mold cavity and which blow-pipe is mounted for kswinging movement so that it may be automatically swung out of the path of travel ofthe valve assembly that moves downwardly into position on top of the casting ring. l l n Further ,objects of myinvention are, yto provide a dental casting machine wherein fluid pressure is utilized formovingthe air control valve downwardly'unto lthe casting ring and to utilize the engagement. between the lower portion of the air controlvalve-and the casting ring for releasing fluid pressure that is eifective iii-forcing the molten metal into the moldcavity and further, to :provide the casting ring with a separately formed 5@ provided with depending hooks or a-nges top plate that is provided with a relativelyl that yare imbedded or anchored ,in the upper portion yof the body of'investment material, thereby greatly yfacilitating and rendering more eiective, the casting koperation and producing increased density in -theffinished castings.,y v 1' liti the `foregoing and other objects in view, my invention `consists in certain novel features of construction and arrangement of parts that will hereinafter 'be `more fully de- 60 scribed and claimed and illustratedin the accompanying drawing, in which:

Fig. y1 yis a vertical section taken through i the centerfofa dental casting machinecon-y structed in kaccordance with my invention, parts thereof being in full side elevation.

Fig. 2`is anenlarged vertical sectiontalen through the center ofthe compressed air control valve and showing the lower end of said valve in contacty with the top plate ofthe casting ring. I

Fig. 3 is an enlarged elevational view of the torch or blow-pipeand which view is taken looking in the direction indicated by lthe arrow `in 1. y

Fig. 4i sl a cross section taken on the line 4 4 ofFig. 2.

Fig. 5 is a cross section taken on the line f 5-.5o`fFig.2.vz V, y, .i

l Fig. 6"`is a detail sectional view ofa por-.80

tion of the cover'plate forthe casting ring and showing' one of the hook-shaped plugs that dependfrom the underside of said plate.

' `Fig. 7 `iis an',enlargedhorizontal section taken onthelineZ-V-' ofFig. 1. j

l "Referring bv numeralsk tothe accompanyinyy drawingwhichillustrates a practical em# bodiment of my -invention`,`10 designates a baseplate, .11 posts thatv project vupwardly therefrom. 12 airing that is Vsupported by' said posts and r13, a cylinder that is mounted on said'ring."y

l A plate 12,a is screw seated in ring 12 and forms Va bottom lfor cylinder 1 3 and formed j through saidfplate 12a are Openings 12".

f The upper face'of base plate 10 is recessed as ydesignated 1,5 yfor the reception ofay casting ring 16" that 'receives` the investment material 17Aand positioned o n top of ring 16 is a separatelyiformed metal plate 18 pro- 10Q lll vided with a centrally arranged opening 19 that is surrounded by a short upwardly projecting flange 20.

Formed on the underside of the top plate 18, adjacent to its edge, is a depending circular flange 20"L the diameter of which is slightly less than the internal diameter et the casting ring 1G and which arrangement permits the separately formed top plate 18 to automatically adjust itself when positioned on the casting ring and the investment material positioned therein.

Depending from the underside of top plate 18 is a plurality of short hooks 21 which when the plate is positioned on top of the rin g, imbed themselves in the upper portion of the body of the investment material, thereby anchoring the top plate to the casting ring when the investment material hardens.

Arranged for reciprocatory movement within cylinder 15 is a piston 22 that is carried by the upper end of a piston rod 23, the latter operating through a bearing 24 in plate 12a and suitably secured on the lower yend of said piston rod is a head 25.

interposed between piston 22 and the bottom of cylinder 13 is an expansive coil spring 2G that normally holds the piston 22 at the .upper end of its limit of movement.

Secured on the side of plate 12L is a bracket 26 upon which is mounted a pressure regulating valve 27 and leading thereto is a flat pressure supply pipe 28. Connected to the pressure regulating valve 27 is a pressure gauge 2S) which is used to indicate the pressure of the air or other fluid that is controlled by valve 26.

Leading from the fluid pressure line 28 that leads to the regulatingr valve 27 is a flexible tube 30, the same being connected to a manually operable valve 31 that is connected to the cap that closes the upper end of cylinder Carried by the lower end ot bracket 26 is a block 32, through which is formed a duct 83 and connected to one end of said duct is a tube 34 that leads from a suitable source of combustible gas` supply.

Secured to the underside of block 32 and communicating with the duct 33 there through is a valve 35 and projecting from one side thereof is a tubular arm 36, to which is connected the upper end of a torch or blowpipe 37 and which is bent so that its lower end occupies a position just above the center of the top plate of the casting ring.

The lower end of this torch or blow-pipe carries a jet nozzle 38.

Secured to tubular arm 36 and projecting outwardly and upwardly therefrom is an arm 39 and the upper portion thereof is adapted to be engaged by the outer portion of an arm 40 that projects outwardly from head 25.

As a result of the construction just described the blow-pipe or torch 37 is swung laterally when the head 25 carrying the arm 40 moves downwardly so as to position the compressed air control valve on top of the casting ring as will be hereinafter more fully described.

Depending from head 25 is a cylinder lug 41 and the lower portion of this lug is rcduced in diameter, thereby forming a shoulder 42 and formed axially through head 25 and lug 41 is a duct 43, the lower portion of which is internally threaded.

Screw seated in the threaded lower end of the duct 43 is a plug 44, through which is formed an axial opening 45 and formed on top of this plug around the opening therethrough is a valve seat 46.

Adapted to rest on seat 46 and to normally close the opening 45 through plug 44 is a valve 47 that is carried by a non-circular stem 48 that passes through opening 45 and the lower end of said stem projects a short distance below the lower end of plug 44.

Stem 4S projects upwardly from valve 47 through opening 43 and the upper end of said stem projects into a recess 49 that is formed in the lower end of piston 23. Positioned on the upper portion of stem 48 and interposed between valve 47 and the lower end of stem 23 is an expansion spring 47,

Arranged for sliding movement on the lower portion of lug 4l is the upper portion of a sleeve 50 and projecting inwardly from the upward portion of said sleeve is a flange 51. This flange is positioned above a flange 52 that projects outwardly from the lower end of plug 44 and this arrangement of flanges'prevents the sleeve 50 from dropping oftq the lug 41.

Flange 51 is positioned between shoulder 42 and the flange 52.

Formed on the lower end of sleeve 50 is a ring plate 53 from the edge of which depends a flange 54 and arranged on the underside of said plate within said flange is a disc 55 of asbestos or analogous fibrous inaterial that is adapted to rest on top of flange 2O during casting operations.

Screw seated in the lowei` end ot sleeve 50 is a ring 56 on top of which is loosely arranged a disc 57 and formed on the underside ol the center of said disc is a lug having an inclined upper edge. Formed through disc 57 immediately above the inclined upper edge of lug 58 is a series of apertures 59.

Connected to the lower portion of the pressure regulating valve 27 and extending downward througfh the upper portion of bracket 26 is a. tube (l0 and leading theretroni to the opening 43 through head 25 is a duct 61. a portion of wl ich is flexible.

Under normal conditions spring` 23 holds piston 22 and piston rod 23 at the upper ends of their travel and the air control valve carried by the lower endo the pistonv rod 'is likewise retained at the upper end ofrits terial immediately above thesprue, the operator swings blow-pipe37 inwardly and ldownwardly so as to position the jet nozzle 38 directly above the metal pellet asy illustrated in Fig. 1.

While the blow-pipe isy shiftedinto its out-of-the-way position valve 35 is] closed yso that the movement of swinging said blowpipe downwardly into position for'use opens` valve 35 and the gaseous mixturel from supply pipe 34 is thus permitted to flow through the open valve and the blow pipe. g Asythe gas from the jet nozzle 38qis ignited' and burns it will melt thevmetal positioned on the investment material and when the metal hasfthus been melted the operatormanually opens valve 31, thereby admittingfiuid pressure from supply line 28 through flexible tube 30 to` the Yinterior of cylinder 13 above -to form a removable closureor `the lower piston 22 and the pressure of the admitted fluid forces piston 22 and parts carried thereby downwardly.

As head 25, carried by valve stem 23, moves downward7 arm 40 that projects from said head, engages the upper end of crank arm 39 and as the downwardmovement continues the blow-pipe 37 will be automatically swung laterally out of the path of travel of the lower portions of the air control valve carried by the lower portion of head 25 and as the tubular arm 36 that carries the blowpipe is thus swung laterally the valve that controls the blow of gas throughthe blowpipe will be cut off. f

As the head 25 and parts carried thereby move downward the asbestos disc 55 will engage the flange 20 on the top plate of the casting ring, thereby preventing said disc` and sleeve 50 from moving any further in a downward direction and headv25 will continue to move downward and 1n so doing` it will slide downwardly through the uppen Y on the reciprocatinghead25 `providesmeans portion of sleeve 50. Y

As the lower end of stem- 48 engages the upper face of disc 57 which is at rest, said stem will be stopped against further downward movement and as head 25 continues to move downward valve 47 Carried `by said stem will leave its seat 46, thus permitting air to pass from regulating valve 60 through duct 61 into axial opening 43 and thus air passes downwardly through opening 45 in plug i y Y 'plate is firmly.' anchored in position during 44 and which air passes through openings 59 and thence through ring 56 and throughv the central portion of fibrous disc 55 and such air pressure is effective in forcing the molten metal into the matrix or mold cavity within the investment material 17.

vAfter the casting operation, as just de.- scribed, has been eiected, the operator closes valve31. and the power stored in 'coilspring 2.6fwill` elevate piston 22 and piston rod `23, thereby elevating head-25 and the air control valve :carriedthereby. i The air vpreviously -admitted Athroughy valve 31 into vcylinder 13 to force the piston'22 downwardly will,I when said valveis closed, escapethroughia kport 31a that is formed inthe sidek of the valve plug .and whichr communicates at its yupper end withthe atmosphere (see Fig. 7 )L After vthe air control valve has been elevated a short distance or a distance ysuiicientto move f fibrous disc 55 away from flange 2O spring 47a-will act to reseatvalv'e47, therebycuttingojthefurther flow of air through'plug y 44 and by gravity sleeve 50 and parts carried thereby will moveV downward until flange 51 rests on flange 52. Y i

The` construction and operation ofthe air control valve forming apart of my 'present invention is practically the same as the air control valve disclosed inL my aforesaid `copending application for patent.

`Plate 12a isscrew seated 1n ring 12 in order i end-or" cylinder 14- and by removing this plate theentires air control :valve `and thepiston and piston rod associated therewith maybe removed from cylinder. 13., l y e. The. openings 12b'fin'plate 12a Vpermits air beneath ythe piston 22 to discharge from the cylinder as said piston moves downwardy as a result'of air pressure yadmitted tothe cyl"- inder above saidvk piston. y y Among the particularlyadvantageous features .of my present inventionarethe swinging blow-pipe or torch and the rcasting ring. Thablow-pipe is mounted so that when v swung inwardly into operative positionthe jet nozzle on the lower end of the pipe is positioned directlyaboveA the sprue that leads to the matrix yor mold; cavity in the investmentr material and this swinging movement V'110 automatically opens valve 35 topermitcombustible gases toilow through-the blow-pipe.

The mounting of the arm39 on theupper portionvof the blow-'pipeyandj the arm/l0 forfautomatically swinging the blow-pipe out of .theway of; the descending lair` control valve and the lateral swingingimovement of the blow-,pipe automaticallycloses the combustible gas rcontrol valve 35.`

The dependingv curved lugs of hooks 21 onthe top plate 425 ofthe casting ring are imbedded' in the investment material contained `within the castingringso lthat theutop The opening-*219 i the top plate 18 of theV casting ring is l compar atiyely y,small and 13o .y

the air that is admitted from the air control valve to force the molten metal into the mold cavity is confined to a. comparatively small space with the result that the density of the casting' is greatly increased.

Thus it will be seen that I have provided a dental castinO' machine that is relatively simple in construction, practically automatic in operation and very effective in performing the functions for which it is intended.

It will be understood that minor changes in the size, form and construction of the various parts of my improved dental casting` machine may be made and substituted for those herein shown and described without departing` from the spirit of my invention, the scope of which is set forth in the appended claims.

I claim as my invention:

l. In a dental casting machine. a. casting ring, a cover plate therefor. which cover plate is provided with a. Centrally arranged opening and lugs depending` from the underside of said cover plate.

2. In a dental casting' machine, a casting,` ring, a cover plate therefor. a ring flan ge depending from the underside of said Cover plate, the diameter of which flange is less than the internal diameter of said casting ring and lugs depending from the underside of said cover plate.

3. In a dental casting' machine. a base, a ring supported above said base, a cylinder sup ported by said ring, a plate removably positioned within said ring` and forming a lower l hea-d for the cylinder, a piston arranged for operation within the cylinder, a piston rod extending from said piston downwardly through said plate, a fluid pressure control valve carried by the lower end of said piston rod and a` casting' ring removably positioned on said base.

4. In a dental casting machine, a base. a ring supported above said base, a cylinder supported by said ring, a plate removably positioned within said ringr and forming a lower head for the cylinder, a piston arranged for operation within the cylinder, a piston rod extending` from said piston downwardly through said plate, a fluid pressure control valve carried by the lower end of said piston rod, a casting ring removably positioned on said base, means for admitting;- fluid pressure to said cylinder above the piston therein and means for admitting fluid pressure to said control valve.

5. In a dental casting machine, a base, a casting ring removably positioned on said base. a` removable top for said casting` ring, a cylinder fixedly supported above said base and casting` ring. a piston arranged for operation within said cylinder, an expansive spring arranged beneath said piston and normally tending to elevate the same, a piston rod extending downwardly through the cylinder from said piston, a valve Carried by the open to atmosphere when said valve is closed.

7. A dental casting machine, as set forth in claim 5, and with a valve xedly supported abovel the base, a. blow pipe connected to the stem of said valve and projecting downwardly and laterally therefrom and means carried by the piston rod for engaging said blow pipe duringthe downward movement of said piston rod and swinging said blow pipe laterally out of the path of travel of said piston rod and the parts carried thereby.

In testimony whereof I affix my signature.

WALTER G. E. HARVEY. 

